Train control



TRAIN CONTROL Filed April 12, 1924 CD d i m m a d FIG 1.

jg? I w la v [taxi/ma Patented Dec. 22, 1925.

tlN-i'lE STATES PATENT OFFICE.

WADE I-I. REICl-IALRD, OF ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAILWAY SIGNAL GOMIEANY, OF ROCHESTER, NEW YORK.

TRAIN CONTROL.

Application filed April 12, 1924. Serial No. 706,117.

To all "to/10m it may concern:

Be it known that I, lVAnn I-I. REICI-IARD, a citizen of the United States of America, residing at Rochester, in the county of Menroe and State of New York, have invented certain new and useful Improvements in Train Controls, of which the following a specification.

This invention relates to automatic train control systems for railroads, and more particularly to the type of system which is eommonly. known as a continuous inductive track circuit control system.

It is sometimes necessary to apply the so called continuous control system to railroads having direct current track circuits fed from storage batteries kept charged by the floating or trickle charge system from an alternating current transmission line. In the continuous control system. as now commonly known, an alternating voltage of a suitable frequency is impressed across the track rails at the exit end of each block, providing an alternating currentfiowing in opposite direct-ions in the track rails ahead of an approaching train; and this track phase or loop circuit current is picked up by suitable receiving. coils on the following train amplified and employed to control the operation of a suitable electro-responsive device on the train. The floating charge system produces across the terminals of the track battery, and hence across the track rails, arectified pulsating voltage. If the track battery should become open-circuited for any reason, the full value of the charging voltage is impressed across the track rails, and the pulsating current may improperly supply energy to the receiving coils on a train, causing a false clear failure. Also, if the vibrator of the rectifier should'become stuck in the circuit closed position v an alternating voltage is impressed across the track battery, and enough pulsating current is supplied to the track phase or loop circuit perhaps to cause false operation of the relay on an approaching train.

In accordance with the present invention, it is proposed to eliminate the possible dangers of false operation due to causes such as just explained, where continuous control is charging line for the floating charge system.

applied to a floating charge direct current track cir-vit system. This is accomplished by opening the charging circuit for the track battery of a g iye n {block when the next block in advance is occupied and it is desired to control a train in said given block.

Various specific objects and advantages of the invention will appear as the description progresses.

In describing the nature of the invention, reference will be made to the accompanying drawing which shows in a simplified and diagrammatic manner specific embodiments of the invention; and in which F 1 shows trackway and car equipment of one form of a continuous inductive train control system embodying this invention: and

Fig. 2 is a fragmentary view showing a modified arrangement of track equipment at the adjoining ends of adjacent blocks, this modification illustrating how the charg- 'ing current for track batteries may be utilized. if desired. for train control purposes- Referring to Fig. 1 of the accompanying drawing, the invention has been shown applied to a continuous inductive control system of the single phase or two-position type, in which two controls are available, corresponding to train control current on, and train control current oil". The track rails 1 are divided by insulated joints 2 into blocks in the usual way. only one complete block B being shown with the adjacent ends of the two other blocks A and G. Since the parts and the circuits associated with several blocks are assumed to be the same, like parts and circuits will be designated by the same reference characters with distinguishing exponents. Each block is provided with a track relay 3 of the usual and well-known construction and a track battery l, which in this instance is a storage battery. The system of train control may be used with or without trackway block signals. Semaphore signals S are shown conventionally at the entrance to each block, without attempting to illustrate their control circuits which may take any one of the well-known forms.

Extending along the railroad is a transmission line T, supplied with alternating currentof a suitable frequency from a generator 5. This transmission line T is the Across this transmission line T are connected the primaries of transformers 6, the secondaries of which are connected to the track batteries 4, by a charging circuit the usual way. Each charging circuit includes a rectifier R, of suitable construction, assumed to be of the vibrator type, although a vacuum tube rectifier may be used, and the front contact 7,0f the track relay 3 of the block next in advance. This circuit includes, in practice, suitable limiting or adjusting resistances and other devices in conformity with recognized practice; and except for the front s11) lied from a se arate enerator 8 on the assumption that, in the interests of cheapness, the transmission line T for charging the batteries may have been installed in such a way that the voltage regulation and current carrying capacity is not well adapted to the supply of train control current. The transmission lines T and T may be of same frequency, preferably a commercial frequency, such as sixty cycles, or may be of different frequencies. A single transmission line may be used, of course, for supplying the charging current and the train control current. i

In series with track battery 4 of each block is the secondary of a transformer 9, the primary of which is connected across the transmission line supplying the train control current, in this instance, the trans mission line T and the circuit for this primary includes the front contact 10 of the track relay 3 of the block next in advance, or a circuit controller on the corresponding block signal, or the front contact of a line relay, or an equivalent circuit controller, this control being such that when there is a train in a given block, the primary circuit of the transformer 9, .supplying train con.- trol to the next block in the rear, is on open circuit.

The car equipment is shown in a simplified and diagrammatic manner. In front of the first pair of wheels and axle 11 of the locomotive or other railway vehicle, are piclcup or receiving coils 12 of usual construction, which are connected in series in such a way that the voltages induced therein by currents flowing in opposite directions in the track rails are cumulative or add together. These coils are preferably resonated in conformity with practice now com- ,monly recognized, and are connected to the input of a suitable amplifying device, shown conventionally and designated AD. The output of this amplifying device AD is connected to a suitable electro-responsive device or relay 15. If the amplifying device AD includes a rectifier tube and gives a unidirectional output voltage, the relay 13 may be a direct current relay of the tractive type; or, if the output voltage is alternating in character, the relay 13 may be a split-phase alternating current relay of the inductive type.

The particular type of train control apparatus itself forms no part of the present invention, and has been shown conventionally and designated K. The primary controlling instrumentality of such traincontrol apparatus K is included in a normally closed circuit which is opened upon deenergization of relay 13. The train control apparatus K preferably includes a speedresponsive device and provides for automatic brake applications only if predetermined speed limits are exceeded. For instance, this train control apparatus K may be of the type shown in the patent to Simmen. No. 1,150,309, August 17, 1915.

The characteristic features of operation of the type of continuous inductive control system shown will be readily understood by those skilled in this art. While the train is traveling in a clear block, alternating train control current is supplied to the track rails ahead of the train, picked up by the receivers 12, amplified, and used to maintain the relay 13 energized and the train control apparatus K inactive, so far as enforcing the cautionary control is concerned. WVhen the train enters a caution block, that is, a block next in the rear of the one occupied by another train, this train control current is cut off and the relay 13 is de-energized, setting the train control. apparatus K into operation. The relay 13 remains (lo-energized in a danger or occupied block, irrespective of the presence or absence of other trains in the block next in advance, because the train ahead in such occupied block shunts the train control current, if any should be supplied to the track rails of that block. Whenever a block chan es from caution to clear, the relay 13 on the car is re-energized.

Referring now to the nature of this particular invention, it will be observed that whenever a train is in a block, as the block B, the front contact 7 of the track relay 3 of said block opens and breaks the charging circuit for the track battery 4 of the blocl: A next in the rear. Consequently, even though the track battery 4 may be opencircuited or, due to sulphation or otherwise, is of high resistance,'or the rectifier R is stuck or out of order, there is no chance for a pulsating or fluctuating voltage, unidirectional or alternating, to be applied across the track rails of the block A, if the block B is occupied. Irrespective of any clerangeinents of the track battery or charg til the supply train in the block next in advance.

ing circuit, therefore, there-isno chance for of varying voltage across the track rails of a block, if the next block in advance is occupied, and hence no possiblechance of a false operation of the train control apparatus on a following train due to such derangements. Track battery is normally on floating charge, "but its charging circuit is broken so long as there is a Such temporary interruptions of the charging, however, do not prevent proper operation ofthe floating charge system, which is effective in the usual way at all times except when a train is passing.

The arrangement shown in Fig. 1 and hereinbefore described is based on the theory of rendering inetl'ective any improper voltages across the track-rails that might be derived from the floating charge system, when a train is present and it is desired to communicate a stopping influence to a following train. In this arrangement of Fig. 1 an additional transformer and track relay control of its primary circuit are used to provide the regular alternating current for train control purposes. Under some conditions and circumstances encountered in practice, it may be expedient to utilize the pulsating voltage that can be derived from the floating charge system for train control purposes and as a substitute for the regular alternating current impressed upon the track rails, inasmuch as such voltages resultant from the charging circuit should, as already explained, he cut olf in the interests of safety if the next block in advance is occupied. A modified arrangement following this expedient is shown in simplified form in Fig. 2.

Referring to Fig. 2, which shows only the trackway equipment at one signal location, the balancing or limiting resistance 14:, commonly used in series with the track battery to regulate the amount of track circuit current, is placed in series with the track battery 4 as usual, but the charging circuit including the rectifier is connected across this resistance and track battery together, rather than across the track battery alone. The connections are clearly indicated in Fig. 2, in which the same reference numbers heretofore mentioned have been used with distinctive exponents. The resistance 14 may include the resistance commonly employed in the charging circuit and in series with the rectifier R, as well as the track circuit limiting resistance.

It will be evident that the inclusion of this resistance 14 in series with the track battery 4, which being a storage battery has ordinarily a relatively low resistance, maintains the terminal voltage of the charging circuit and applies this voltage across the track rails, thereby giving a u 'ii-directlonal pulsating voltage which can be made of such magnitude as to provide suliicient current for train control purposes. In this modified construction of Fig. 2, the prin'iary circuit: for the charging transformer (1 is taken through the front contact of the track relay of the block nextin advance, rather than the secondary circuit. This a1- rangement is considered preferable in some respects, particularly because it places the variable contact resistance of the tract; relay in that circuit where it is least detrimental. @bviously, the same arrangement of control for the charging circuit may be used in Fi 1.

Vv'hile the invention has been shown applied to a single phase or two-position type of system, it is obviously applic: ble to continuous control systems of other types where it is necessary to cut oil? the track phase or loop circuit current to produce auton'iatic control, and where an improper substitute from the floating charge systen'l might pro duce false operation. The invention and its application have been shown in the simplest form; and it should be understood that various auxiliary arrangements and adjuncts in conformity with recognized practice are conten'iplated. I desire to have it understood, therefore, that my invention is not restricted to the specific form, construction and arrangement of parts and. circuits shown and described, but is broad in its character.

What I claim is 1. In a continuous inductive train control system for 'ailroads, equipped with direct current track circuits and a floating charge system, the combination with the track bat-- tery and its charging circuit, of means for interrupting said charging circuit whenever the next block in advance is occupied.

2. A train control system of the character described, having in eombiuatimi with a track battery and a charging circuit therefor, a circuit controller in said charging circuit opened whenever the next block in advance is occupied.

3. In a train control system for railroads having blocks equipped with direct current track circuits, means for supplying alternating current across the track rails at the exit end of each block in series with the track battery, only if the block next in advance is not occupied, a charging circuit for the track battery including a source of alternating current and a rectifier, and means for interrupting the charging circuit for the track battery of each block if the block next in advance is occupied.

4. In a train control system for railroads, equipped with direct current track circuits. the track batteries of which are maintained charged by a floating charge system, means controlled in accordance with traflic conditions for impressing across the track rails at the exit end of each block a fluctuating voltage, provided the next block in advance is not occupied, and means for preventing the application of such fluctuating voltage from the floating charge system.

5. In a train control system, the combination With a direct current track circuit having a storage battery for the track battery,

age from said source under said predetermined traffic conditions.

,6. A system of train control of the character described, comprising in combination With direct current track circuits and a floating charge system for the track batteriesthereof, means for interrupting the charging of each track battery While the track of the block in advance is occupied.

7. In a train control system, the combination with a direct current track circuit having a storage battery for the track battery connected across the track rails in series with a resistance, a source of alternating current and a rectifier supplying a uni-directional pulsating voltage across said battery and resistance, and automatic trafiic controlled means for governing the supply of said pulsating voltage.

8. In a continuous inductive train control system for blocks equipped with direct current track circuits, the combination With'a storage battery connected across the track rails at the exit end of each block, of trafiic controlled means for charging said storage battery and providing a pulsating inter-rail voltage for train control purposes.

9. A continuous inductive train control system characterized by the use of a storage battery and a charging circuit automatically controlled in accordance with t-raflic conditions to provide a charging current for the battery and a train control current.

In testimony whereof I aflix my signature.

WADE H. REIOHARD. 

